<!DOCTYPE html>
<html>

<head>
  <meta charset="utf-8">
  <title>setTransform</title>
</head>

<body>
  <canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;">
    您的浏览器不支持 HTML5 canvas 标签。
  </canvas>
  <script>
    var c = document.getElementById("myCanvas");
    var ctx = c.getContext("2d");
    ctx.fillStyle = "yellow";
    ctx.fillRect(0, 0, 250, 100)
    ctx.setTransform(1, 0.5, -0.5, 1, 30, 10);
    ctx.fillStyle = "red";
    ctx.fillRect(0, 0, 250, 100);
    ctx.setTransform(1, 0.5, -0.5, 1, 30, 10);
    ctx.fillStyle = "blue";
    ctx.fillRect(0, 0, 250, 100);
  </script>
</body>

</html>